Unlike the pointy chins of humans, chimpanzees have receding chins lacking many of the lip muscles of humans.
A. Chimpanzees have receding chins lacking - chins of humans are compared to chimpanzees. This is incorrect comparison.
B. a chimpanzee has a receding chin lacking - chins of humans are compared to a chimpanzee. Again, incorrect comparison.
C. that of chimpanzees are receding lacking - While the comparison makes perfect sense, this sentence has introduced a new error. "..receding lacking.." This usage is incorrect in any GMAT style question. There should be 'because'/ 'as'/ 'since' after receding to show the 'how' aspect.
D. the chins of chimpanzees are receding, lacking - Correct choice as it corrects the comparison error of (A) and does not introduce any new error. Verb-ing modifier lacking present the how aspect of the preceeding clause.
E. that of a chimpanzee is receding which is lacking - comparison issue of (A) has been resolved. However, the usage of 'which' is incorrect. Which can only refer to nouns, and mind you the nearest noun entity and that noun entity must be placed right before which. (EXCEPTIONS are there to this rule though, if you want to know more, feel free to reach out).
So coming back to the question, the nearest noun preceeding which is chimpanzee. However, it is incorrect to say that chimpanzee lacks many of the lip muscles of humans. On the contrary, the chins of chimpanzees lack these muscles. Thus, this option is incorrect.